Comet Hartley 2 contains water more like that found on Earth than prior comets seem to have, researchers say.

A study using the Herschel space telescope aimed to measure the quantity of deuterium, a rare type of hydrogen, present in the comet's water.

The comet had just half the amount of deuterium seen in comets.

The result, published in Nature, hints at the idea that much of the Earth's water could have initially came from cometary impacts.

Just a few million years after its formation, the early Earth was rocky and dry; something must have brought the water that covers most of the planet today.

Water has something of a molecular fingerprint in the amount of deuterium it contains, and only about a half-dozen comets have been measured in this way.

All of them have exhibited a deuterium fraction twice as high as the oceans, so the current theory holds that asteroids were likely to be the carriers for water; meteorites that they give rise to have roughly the same proportion of deuterium that the Earth's oceans contain.

1 In the beginning God created the heavens and the earth. 2 Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters.

3 And God said, Let there be light, and there was light. 4 God saw that the light was good, and he separated the light from the darkness. 5 God called the light day, and the darkness he called night. And there was evening, and there was morningthe first day.

6 And God said, Let there be a vault between the waters to separate water from water. 7 So God made the vault and separated the water under the vault from the water above it. And it was so. 8 God called the vault sky. And there was evening, and there was morningthe second day.

9 And God said, Let the water under the sky be gathered to one place, and let dry ground appear. And it was so. 10 God called the dry ground land, and the gathered waters he called seas. And God saw that it was good.

How much water is in a comet compared to that in the earth’s oceans? Is it plausible that a strike on the earth by a large dry rock could cause ocean water to splash out into outer space, in such a way that it would enter a highly elliptical orbit about the sun and become a comet?

How much water is in a comet compared to that in the earths oceans? Is it plausible that a strike on the earth by a large dry rock could cause ocean water to splash out into outer space, in such a way that it would enter a highly elliptical orbit about the sun and become a comet?

One of the links in the comments above has something about a whole lot of comets over a long time period.

I thought it was hilarious how the radar data of small meteorites, the 1980s small comet satellite data, and the 1990s small comet satellite data all give exactly the same graph. And that astronomer who developed the skeet shoot method of getting an exposure on these objects was great. Too bad he died so soon. I think it was diabetes.

Something everyone who accepts the reality of stones falling from space but not water should remember is what the scientists were saying about folks who claimed that stones were falling to the ground from space back in the 18th century:

The German physicist, Ernst Florens Chladni, was the first to publish the then audacious idea that that meteorites were actually rocks from space.[35] He published his booklet, "On the Origin of the Pallas Iron and Others Similar to it, and on Some Associated Natural Phenomena", in 1794. In this he compiled all available data on several meteorite finds and falls concluded that they must have their origins in outer space. The scientific community of the time responded with resistance and mockery.[36] It took nearly 10 years before a general acceptance of the origin of meteorites was achieved through the work of the French scientist Jean-Baptiste Biot and the British chemist, Edward Howard. Biot's study, initiated by the French Academy of Sciences, was compelled by a meteorite fall of thousands of meteorites on April 26, 1803 from the skies of L'Aigle, France.[37][38]

I have a feeling that this "community" is a lot more resistant now to new ideas than it was then. Of course, that very public fall of thousands of meteorites in France helped a lot. Too bad we couldn't luck out on this one with something like that over, say, Washington, D.C..

The result, published in Nature, hints at the idea that much of the Earth's water could have initially came from cometary impacts.

I haven't pulled out my slide rule, but I have a *problem* with that theory.

To wit: If you calculated, or estimated, the volume of all the water in the earth's oceans (not even all the lakes and rivers), then factored in the size of the 'average' comet head containing ice you would need a 'googol' of Comets hitting the earth during its 'formative' years - after it cooled but had no water.

Then after 'a while' (scientific term) some of that water would have formed a young atmosphere creating friction for the latter comets with water ice hitting the earth, which would evaporate the water into a gas. And that friction factor would then increase exponentially ('e') as our atmosphere increased. And keep in mind the comet(s) couldn't be too large or the debris field expelled 'up' would create an added friction factor for the other comets to pass through.

Granted, the young solar system was a violent place, just look at the moon. But comets being the source of all our water? I can't imagine the number ('n') of comets involved which would result in getting a '+' = 'water'.

Think I'll fire off an email to Stephan Hawking today for his take on this.

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